1. Field of the Invention
The present invention relates to an electric discharge lamp lighting unit for lighting an electric discharge lamp used as a headlight in a vehicle such as an automobile.
2. Description of the Related Art
The beam strength and lamp efficiency of high intensity discharge lamps (HID) such as metal halide lamps, high-pressure sodium lamps, mercury lamps and the like is very high. In addition, conventionally, the life span of such lamps is high. In view of such advantages, such lamps have been used in indoor applications such as warehouses and factories and in outdoor applications as street lamps. In particular, in recent years, such lamps have been used as vehicle headlights in automobiles and the like. Since it is necessary to apply a high voltage starting voltage in order to light such lamps, it is necessary to provide an igniter which generates a starting voltage and add a ballast in order to light the discharge lamp in a stable manner.
FIG. 1 is a cross section of the interior structure of a high voltage generating transformer used in a conventional discharge lamp. In the figure, reference numeral 1 denotes a high voltage-generating transformer. The high voltage generating transformer 1 is schematically shown as comprising a columnar core 2 disposed in the center of the transformer, a primary coil 3 wound on the periphery of the core 2, a secondary coil 4 wound on the outer side of the primary coil 3 and an insulating member 5 which insulates between the primary and secondary coils 3, 4.
Since the high voltage generating transformer 1 in the conventional discharge lamp is constructed as above, the secondary coil 4 which acts as a high voltage generating section is near the low voltage core 2 and the periphery of the low voltage core 2. As a result, it is necessary to create an insulating distance L with respect to high voltage between the core 2 and the secondary coil 4 and between the secondary coil 4 and its peripheral components. Therefore the insulating member 5 must be of a minimum thickness. As a result, the problem of reducing the size of a lamp which is to be mounted in an automobile for example has arisen.
The present invention is proposed to solve the above problems and has the object of providing a small sized electric discharge lamp lighting device which can generate a high voltage.
The electric discharge lamp lighting device of the present invention disposes a secondary coil for the high voltage generating transformer on the core side and a primary coil on the outer side of the secondary coil. A high voltage terminal for the secondary coil is connected to a terminal of the core and a low voltage terminal of the secondary coil is connected to the primary coil. In such a way, it is possible to reduce the insulating volume and the number of components as well as reduce the size of the unit.
The electric discharge lamp lighting device of the present invention achieves a reduction in the size of the electric discharge lamp lighting device by reducing the size of the high voltage generating transformer as a result of integrating the bobbin of the high voltage generating transformer with the connector used to connect the discharge lamp.
The electric discharge lamp lighting device of the present invention facilitates insulation by maintaining the distance of the peripheral members in order to concentrate the secondary coil, which generates a high voltage, in the center of the high voltage generating transformer by providing the high voltage generating transformer on the axis of the high voltage terminal of the discharge lamp.
The electric discharge lamp lighting device of the present invention achieves a reduction in the size of the electric discharge lamp lighting device by reducing the size of the high voltage transformer by integration of the holder which holds the core of the high voltage transformer with the terminal of the core.
The electric discharge lamp lighting device of the present invention achieves reductions in costs and the size of the mold by the provision of a partition which fixes only the high voltage generating transformer in the case into which the high voltage generating transformer is embedded.
The electric discharge lamp lighting device of the present invention simplifies and increases the assembly speed of the electrical connection of the high voltage transformer and the wiring board by projecting a terminal connected to a terminal of a wiring board in the case into the high voltage generating transformer when housing the high voltage generating transformer in the case.
The electric discharge lamp lighting device of the present invention realizes a compact size for the electric discharge lamp lighting device through the creation of an empty space by offsetting the case housing the high voltage generating transformer to one side of the axis of the connector of the high voltage generating transformer and providing a luminous intensity switching motor in the space.